If you’ve ever watched HBO’s “Game of Thrones,” you’ve heard his work coming out of the mouths of Dothraki warlord Khal Drogo and his bride, Daenerys Targaryen. But Dothraki was a piece of cake compared to his work on “Defiance,” whose story involves seven different alien races.

Not only did Peterson imagine their spoken tongues, each with its own internally-consistent syntax and phonetics; in some cases, he had to come with up written languages and even number systems. (For instance, the Indogene people use a base-six mathematics inspired by their hexagonal irises.) Then came the not-inconsiderable task of teaching actors how to deliver his dialogue.

Curious what it’s like to have this most unusual of careers? I chatted with Peterson about which of his languages are his favorites, what’s coming up on “Game of Thrones” and why George R.R. Martin is a surprisingly cunning linguist in his own right.